Regulator circuit for vehicle air conditioner

Abstract

A regulator circuit for controlling the cooling and heating power for automotive vehicles, wherein signals proportional to the external temperature, the internal temperature of the vehicle, and the desired temperature are applied to an input amplifier, the output signal of this amplifier being applied as the desired value to the heating system. This output signal is also fed to a second amplifier which is furthermore supplied with the signal proportional to the external temperature. The output signal of this second amplifier serves as the desired value for the cooling system. By means of this arrangement, excessive cooling at the transition point between heating and cooling, as well as oscillation around this transition point, can be prevented. An economical reheat operation is made possible for dehumidifying the air by appropriate selection of resistor values such that the heating system and the cooling system are in simultaneous operation.

What is claimed is: 
     
       1. A regulator circuit for controlling the cooling and heating system of an automotive vehicle comprising: a first amplifier having an output signal connected to a means for regulating the heating of the vehicle, means for supplying the first amplifier with a signal proportional to the external temperature, means for supplying the first amplifier with a signal proportional to the internal temperature of the vehicle, and means for supplying the first amplifier with a signal proportional to the desired temperature for the vehicle, a second amplifier having an output signal connected to a means for regulating the cooling of the vehicle, means for supplying an input of the second amplifier with the output signal of the first amplifier, and means for supplying the input of the second amplifier with a signal proportional to the external temperature of the vehicle.   
     
     
       2. The regulator circuit of claim 1 wherein the first amplifier and the second amplifier are connected as summing amplifiers. 
     
     
       3. The regulator circuit of claim 1 further comprising means connected to the input of the second amplifier for weighting the signal proportional to the external temperature. 
     
     
       4. The regulator circuit of claim 1 further comprising resistor means connected in the input circuits of the first and second amplifier, the values of the resistor means being selected such that cooling regulation is initiated by the second amplifier only when the first amplifier has caused heating to cease. 
     
     
       5. The regulator circuit according to claim 1 further comprising resistor means connected in the input circuits of the first and second amplifier, the resistor means being selected such that there is a thermal overlap region where the output signals of the first and second amplifiers are both non zero. 
     
     
       6. The regulator circuit according to claim 1 further comprising a limiter means connected to the output of the second amplifier for controlling the maximum output signal value of the second amplifier, and a two-position regulator connected to the output of the limiter means for controlling activation and deactivation of a refrigeration compressor. 
     
     
       7. The regulator circuit according to claim 6 further comprising a relay having a coil connected to the two-position regulator, the relay having contacts closed by a field generated by the coil, the contacts being connected to an electromagnetic clutch for actuating the refrigeration compressor for cooling the vehicle. 
     
     
       8. A regulator circuit according to claim 6 further comprising a temperature probe for generating a signal proportional to the temperature of a cooling evaporator, and means for connecting an output of the temperature probe to an input of the two-position regulator such that the signal proportional to the cooling evaporator temperature is fed back to an input of the two-position regulator. 
     
     
       9. The regulator circuit according to claim 1 further comprising flap control means for controlling the position of a fresh air/recirculated air flap and means for connecting the flap control means to the output signal of the second amplifier. 
     
     
       10. The regulator circuit according to claim 9 wherein the flap control means comprises a relay for controlling the position of the fresh air/recirculated air flap, and a comparator connected to the relay and to the output of the second amplifier, the comparator being set such that the flap is operated to the "recirculated air" position only when the output of the second amplifier achieves a maximum value. 
     
     
       11. The regulator circuit according to claim 1 further comprising a comparator connected to the output of the first amplifier and a servo member connected to the output of the comparator for controlling the flow of water through a heating radiator. 
     
     
       12. The regulator circuit according to claim 1 further comprising a position controller connected to the output of the first amplifier, a servomotor connected to the output of the position controller, the servomotor operating a flap controlling the mixture of heated air and unheated air being introduced into the vehicle, and means for generating a signal corresponding to the position of the flap, the signal being connected to the input of the position controller. 
     
     
       13. The regulator circuit according to claim 11, further comprising a position controller connected to the output of the first amplifier, a servomotor connected to the output of the position controller, the servomotor operating a flap controlling the mixture of heated air and unheated air being introduced into the vehicle, and means for generating a signal corresponding to the position of the flap, the signal being connected to the input of the position controller. 
     
     
       14. The regulator circuit according to claim 6 further comprising flap control means for controlling the position of a fresh air/recirculated air flap and means for connecting the flap control means to the output signal of the second amplifier before said limiter means.